export default {
  namespaced:true,
  
  // PS：箭头函数return的值若为一个对象，要用()将其包裹
  state:() => ({
    // 购物车的数组，用来存储购物车中每个商品的信息对象
    // 每个商品的信息对象，都包含如下 6 个属性：
    // { goods_id, goods_name, goods_price, goods_count, goods_small_logo, goods_state }
    cart:JSON.parse(uni.getStorageSync("cart") || "[]")
  }),
  
  mutations:{
    addToCart(state,goods) {
      const findResult = state.cart.find(i => i.goods_id === goods.goods_id)
      
      if(!findResult) {
        state.cart.push(goods)
      }else{
        findResult.goods_count++
      }
      // 
      this.commit('m_cart/saveToStorage')
    },
    // 把购物车内容存到本地中
    saveToStorage(state) {
      uni.setStorageSync('cart',JSON.stringify(state.cart))
    },
    // 更新购物车中商品的勾选状态
    updateGoodsState(state,goods) {
      const findResult = state.cart.find( x => x.goods_id === goods.goods_id)
      if(findResult) {
        findResult.goods_state = goods.goods_state;
        
        this.commit('m_cart/saveToStorage')
      }
    },
    // 根新商品的数量
    updateGoodsCount(state,goods) {
      const findResult = state.cart.find( x => x.goods_id === goods.goods_id)
      if(findResult) {
        findResult.goods_count = goods.goods_count;
        
        this.commit('m_cart/saveToStorage')
      }
    },
    // 通过商品的goods_id删除指定商品
    removeGoodsById(state,goods_id) {
      // 
      state.cart = state.cart.filter(x => x.goods_id !== goods_id);
      this.commit('m_cart/saveToStorage')
    },
    // 更新所有商品的勾选状态
    updateAllGooodsState(state,newState) {
      state.cart.forEach( x => x.goods_state = newState)
      this.commit('m_cart/saveToStorage')
    }
  },
  
  getters:{
    // 统计购物车中商品的总数量
    total(state) {
      // let sum = 0;
      // state.cart.forEach(goods => sum += goods.goods_count);
      // return sum 
      
      return state.cart.reduce((total,item)=> total += item.goods_count,0)
    },
    // 已勾选的商品的总数量
    checkedCount(state) {
      return state.cart.filter( x => x.goods_state).reduce((total,item) => total += item.goods_count,0)
    },
    // 已勾选商品总价格
    checkedGoodsAmount(state) {
      return state.cart.filter( x => x.goods_state).reduce((total,item)=>total += item.goods_price*item.goods_count,0).toFixed(2)
    }
  }
}